Enzymes’ Power for Plastics Degradation

Abstract

Plastics are everywhere in our modern way of living, and their production keeps increasing every year, causing major environmental concerns. Nowadays, the end-of-life management involves accumulation in landfills, incineration, and recycling to a lower extent. This ecological threat to the environment is inspiring alternative bio-based solutions for plastic waste treatment and recycling toward a circular economy. Over the past decade, considerable efforts have been made to degrade commodity plastics using biocatalytic approaches. Here, we provide a comprehensive review on the recent advances in enzyme-based biocatalysis and in the design of related biocatalytic processes to recycle or upcycle commodity plastics, including polyesters, polyamides, polyurethanes, and polyolefins. We also discuss scope and limitations, challenges, and opportunities of this field of research. An important message from this review is that polymer-assimilating enzymes are very likely part of the solution to reaching a circular plastic economy.

Advancements in catalysis for plastic resource utilization

“…The biocatalytic treatment process for plastics primarily relies on enzymatic catalysis. 88 Nature harbors a vast array of active enzymes and microorganisms that possess the capability to break down plastic copolymers, including PET enzyme (PETases), keratinases, and hydrolases. 89,90 In the case of PETases, Kalathil et al discovered that Ideonella sakaiensis ( I. sakaiensis ), a PETases, can completely mineralize PET into carbon dioxide, water, and adenosine triphosphate (ATP) when exposed to oxygen.…”

Assessment of Four Engineered PET Degrading Enzymes Considering Large-Scale Industrial Applications

“…PET, composed of monomers linked by ester bonds, can be enzymatically hydrolyzed, yielding the products terephthalic acid (TPA) and ethylene glycol (EG), which are suitable for a resynthesis of the polymer after their purification. Nearly 20 years ago, the first hydrolase, a cutinase, was shown to specifically depolymerize PET. , Since then, many other hydrolases have been isolated and enhanced through protein engineering. ,– In 2020, leaf-branch compost cutinase (LCC) was engineered into a quadruple variant called LCC ICCG to meet industrial requirements . This study showed that monomers obtained through enzymatic hydrolysis under industry-relevant conditions could be purified and reused to obtain virgin PET, paving the way for the industrial deployment of enzyme-based PET depolymerization.…”

Whether the wobbling W156 is a pre-requisite for efficient PET biodegradation by IsPETase

“…Plastics have become an indispensable part of modern society due to their remarkable versatility combined with low production costs 1 . However, after years of benefiting from its convenience, people now realized the dire global pollution threat posed by synthetic plastics.…”